263] NOCTVID LARVAE— RIPLEY 21 



development. In the Noctuidae, however, they do not vary markedly, 

 being typically as represented in Cirphis nnipunda (Fig. 24). The chi- 

 tinized areas which occasionally appear in the membranous portion of the 

 submentum in other families are rarely met with in the noctuids. The 

 width and shape of the chitinized portion (Figs. 24, 28, 31) of the stipulae 

 varies considerably according to the genus. Much generic and some 

 specific variation is also presented by the chitinized portion (Figs. 26, 28, 

 31, 38, 44) of the palpiger. In the noctuids this sclerite exhibits a compara- 

 tively reduced condition and never appears as the basal segment of the 

 palpus as it does in some other families. The long and slender type of 

 palpus occurring in a few groups has not been found in the Noctuidae, this 

 appendage exhibiting the stout form most common in the order. It varies, 

 however, according to the genus or to larger groups in relative width and 

 length and in the proportional size of the two segments. The setae of the 

 palpus present differences within the family in form, size, and position. 

 The one borne on the distal end of the proximal segment is usually located 

 laterad of the minute distal segment throughout the order, although in 

 certain noctuid genera it has migrated around the cephalic side of the 

 distal end of the first segment until it appears mesad of the terminal seg- 

 ment, as in Lycophotia margaritosa (Fig. 38), a process revealed by postem- 

 bryonic development. This is the only instance known to the author where 

 a seta of the head or mouth-parts appears to have migrated by itself 

 uninfluenced by movements of the cuticle. Forbes notes and figures an 

 exceptional condition in an unnamed species of Catocala where there is 

 apparently an extra small basal segment of the palpus. A similar develop- 

 ment is often present in the Catocalinae due to the globular shape of the 

 coria proximad of the basal segment. The situation figured by Forbes is 

 evidently due to the secondary chitinization of this coria, the distal portion 

 of the labium of this species exhibiting an unusual amount of chitin gener- 

 ally for a noctuid larva. 



In spite of the very extensive variety of form offered by the spinneret, 

 the amount of investigation which has been performed upon this interesting 

 structure is surprisingly meager. Beyond Lyonet's figures showing the 

 spinneret of Cossus cossus, those by Forbes of a species of Catocala and of 

 Thyridopleryx ephemcraeformis, two by Dampf showing the mouth-parts 

 of case-bearing larvae, and a short series of the labia of leaf-miners by 

 Tragardh, there are no detailed representations of the spinneret known to 

 the author. Yet this organ probably presents a greater range of variation 

 than any other structure of lepidopterous larvae. The proximal semicir- 

 cular sclerite varies much in width and shape, as Forbes has shown. It is 

 typically broken on the caudal aspect, although its mesal ends (Fig. 31) 

 are often joined by secondary chitinization, as in PoHa renigera. This 

 condition may exist in some groups as a primary one, since postembry- 



